title: Reduction of CC-chemokine ligand 5 by aryl hydrocarbon receptor ligands.
abstract: BACKGROUND
  The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that recognizes a large number of xenobiotics, such as polycyclic aromatic hydrocarbons (PAHs), dioxins, and some endogenous ligands. Despite numerous investigations targeting AhR ligands, the precise physiological role of AhR remains unknown.
  
  
  OBJECTIVE
  We explored novel AhR target genes, especially focused on inflammatory chemokine.
  
  
  METHODS
  We treated (1) HaCaT, a human keratinocyte cell line, (2) normal human epidermal keratinocytes (NHEKs), and (3) mouse primary keratinocytes with AhR ligands, such as 6-formylindolo[3,2-b]carbazole (FICZ; endogenous ligand) and benzo[a]pyrene (BaP; exogenous ligand). Then, we detected mRNA and protein of chemokine using quantitative RT-PCR and ELISA. We next clarified the relationship between AhR and chemokine expression using AhR siRNA. In addition, we measured serum chemokine levels in patients with Yusho disease (oil disease), who were accidentally exposed to dioxins in the past.
  
  
  RESULTS
  We identified CC-chemokine ligand 5 (CCL5), a key mediator in the development of inflammatory responses, as the AhR target gene. AhR ligands (FICZ and BaP) significantly reduced CCL5 mRNA and protein expression in HaCaT cells. These effects were observed in NHEKs and mouse primary keratinocytes. AhR knockdown with siRNA restored CCL5 inhibition by AhR ligands. In addition, AhR ligands exhibited a dose-dependent suppression of CCL5 production induced by Th1-derived cytokines. Finally, serum levels of CCL5 in patients with Yusho disease, were significantly lower than in controls.
  
  
  CONCLUSIONS
  Our findings indicate that CCL5 is a target gene for AhR, and might be associated with the pathology of dioxin exposure.
authors.affiliation: Department of Dermatology, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Fukuoka 812-8582, Japan.
authors.forename: Saori
authors.initials: S
authors.lastname: Morino-Koga
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Uchi
authors.forename: Gaku
authors.initials: G
authors.lastname: Tsuji
authors.forename: Masakazu
authors.initials: M
authors.lastname: Takahara
authors.forename: Junboku
authors.initials: J
authors.lastname: Kajiwara
authors.forename: Teruaki
authors.initials: T
authors.lastname: Hirata
authors.forename: Masutaka
authors.initials: M
authors.lastname: Furue
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001564:Benzo(a)pyrene / Q000378:metabolism; D002227:Carbazoles / Q000378:metabolism; D016022:Case-Control Studies; D002460:Cell Line; D002478:Cells, Cultured; D018946:Chemokine CCL5 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004147:Dioxins / Q000097:blood / Q000633:toxicity; D055785:Gene Knockdown Techniques; D006801:Humans; D015603:Keratinocytes / Q000276:immunology* / Q000378:metabolism*; D008024:Ligands; D051379:Mice; D008875:Middle Aged; D011164:Porphyrias / Q000097:blood / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism*
chemical_list: C111855:6-formylindolo(3,2-b)carbazole; C483024:CCL5 protein, human; D002227:Carbazoles; C503460:Ccl5 protein, mouse; D018946:Chemokine CCL5; D004147:Dioxins; D008024:Ligands; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D018336:Receptors, Aryl Hydrocarbon; D001564:Benzo(a)pyrene
keywords: 2,3,4,8-tetrachlorodibenzo-p-dioxin; 6-formylindolo[3,2-b]carbazole; ARNT; AhR; AhR nuclear translocator; Aryl hydrocarbon receptor; BaP; CC-chemokine ligand; CC-chemokine ligand 5; CCL; Chemokines; Dioxins; FICZ; Keratinocytes; NHEK; PAHs; PCB; TCDD; aryl hydrocarbon receptor; benzo[a]pyrene; normal human epidermal keratinocyte; polychlorinated biphenyls; polycyclic aromatic hydrocarbons